Process of making alkyl pyridines



United States PatentO PROCESS OF MAKING ALKYL PYRIDINES ICC 6/1. A suitable catalyst is a silica-alumina catalyst similar to that used for petroleum cracking. An alumina content ranging between and 50% by weight and 95% to 50% by weight silica is satisfactory. An alumina 5 content of 7% to 25% by weight in the catalyst is a Robert J. Zellner, Marinette, Wis., assignor to Ansul Preferred range The catalyst y be p y in y Chemical Company, Marinette, Wis., a corporation of Suitable form, as for example, granules, pellets, powders Wisconsin or fragments of regular or irregular contour and of workable size. The process is carried out at substantially No Drawmg' ig g ggg ggg 10 atmospheric pressure at 300 C. to over 550 C. with operation at about 450 C. belng preferred. 3 Claims. (Cl. 260-290) The following examples will illustrate certain of the numerous possible specific embodiments of the invention. It will be understood that the examples are intended to Thi i ti relates to a process for the production be illustrative of the invention and not limitations thereon of lk l idi M ifi ll hi i ti as it is more broadly disclosed and claimed herein. lates to the vapor phase interaction of ammonia and a A Series of runs was made in an electrically heated selected aliphatic ketone in th presence f a hi hl actor 1 /2 inches in diameter with an eifective catalyst active contact catalyst to produce a valuable pyridine depth of 341/2 lnches- The catalyst Was a Synthetic 13% derivative. The process of this invention is especially usealumina 87% Product PP as lncll diamful for producing 2,4,6-trimethylpyridine. eter by A3 inch long extrusions. Acetone and ammonia Pyridine and its a-lkyl homologs have long been recogwere fed into the top of the reactor via separate supernized as important intermediates in the synthesis of dyehefltel's- The Crude Product was Condensed Wltll a Stainstufis, pharmaceuticals, insecticides and the like as well less steel heat exchanger. Enough flake sodium hydroxide as having valuable applications per se as solvents. These (g y 1/5 the total Weight Condensate) Was added bases are commonly obtained as by-products from coal to saturate the water layer of the condensate. The oil tar production, but when derived fnom this source ar was drawn olf, filtered if necessary, and fractionally diseither relatively impure or are purified by dilficult and/or ltilled at atmospheric p The acetone not used costly procedures. Methods of synthesis of pyridine in the reaction was recovered below 58 C. and recycled homologs, other than obviously impractical classical proto the feed system. The main body of 2,4,6-trimethylcedures, have been confined to condensation reactions of pyridine was collected at 167l69 C. (uncorrected). ammonia with acetylene, alcohol, ketones and aldehydes. Identification was made through the picrate (M. P. 153- For the most part little progress has been made with 156 C.) and the picrolonate (M. P. 230 C.). The these reactions because of the formation of mixtures of distillate was analyzed by infra-red adsorption and a purity pyridines and pyridine derivatives and various by-pnoducts. of 94% to 97% 2,4,6-trimethylpyridine was demonstrat- In addition, when operating according to the prior art, relaed. No. 3,5-dimethylpyridine (the usual contaminant in tively low yields of individual products have usually been coal tar derived material) was found. By comparison, obtained. the best commercially available material (claimed to be It is an object of this invention to provide a novel 97% by the supplier) assayed at 91% and a technical process for the production of substituted pyridines. It grade product indicated about 2,4,6-trimethylpyriis another object of this invention to provide a process dine content. These experiments are summarized in the for the production of substituted pyridines that eliminates following Table I:

Table I Sample No 1 2 3 4 5 6 7 8 9 10 Feed Rate Acetone 505 348 628 628 644 665 920 920 340 318 Ammonia 95 134 114 121 64 110 165 115 131 99 Temperature 400 400 425 450 450 475 475 475 475 500 Acetone Recovered, Wt. percent-.. 34.4 10.3 23.2 23.1 31.3 23.4 27.0 24.4 9.0 9.1 High Boiling Pyridine, Wt. percent 25.5 21.1 19.4 12.5 19.2 12.8 10.0 12.5 9.6 5. v 2, 4. 6-Trlmethylpyridine:

Wt. percent 16.7 14.6 20.1 23.7 15.8 20.8 21.5 18.9 17.2 18.9 Mole percent 24.0 20.9 28.9 34.1 22.7 29.9 30.9 27.2 24.8 27.2

1 Grams/hour/llter catalyst.

the difiiculties of the prior art processes. It is still another object of this invention to condense a ketone and ammonia in the presence of a catalyst for this reaction. Another object of this invention is to provide a novel pnocess for the production of 2,4,6-trimethylpyridine from a boiling ketone and ammonia. It is a further object of this invention to provide a novel process for the production of 2,4,6-trimethylpyridine of high purity and substantially free from rthe contaminants normally found in the coal tar derived product.

My invention comprises essentially the passage of a selected vaporized aliphatic ketone in admixture with ammonia with or without an inert diluent over a catalyst at suitable conversion temperatures. I have found it advantageous to use a weight ratio of acetone/ammonia between 10/1 and 2/1, and preferably between 4/1 and It will be evident that my process makes it possible to produce 2,4,6-trimethylpyridine of high purity and substantially free from the contaminants normally found in the pnoduct derived from coal tar.

Having disclosed the details of my invention, I claim:

1. The process of making 2,4,6-trirnethylpyridine which comprises passing vapors of acetone and ammonia in weight ratio between 10/1 and 2/1 over a silica-alumina catalyst containing between 5% and 50% by weight of alumina and to 50% by weight of silica at a temperature from about 300 C. to about 550 C.

2. The process of making 2,4,6-trimethylpyridine as defined in claim 1 wherein the temperature is about 450 C.

3. The process of making 2,4,6-trimethylpyridine which comprises passing vapors of acetone and ammonia in weight ratio of between 4/1 to 6/1 over a silica-alumina catalyst containing between 7% and 25% by weight of OTHER REFERENCES alumina and 93% to 75% by weight of silica at a tem- Frank et C. S. VOL 71 pages 2629 2635 perature of about 450 C. (1949).

References Cited in the file of this Patent r Riehrn, Beilstein, Handbook of Organic Chem, 4th

0 ed., v01. 1 page 642 (1918). UNITED STATES PATENTS 2,523,580 Mahan Sept. 26, 1950 

1. THE PROCESS OF MAKING 2,4,6-TRIMETHYLPYRIDINE WHICH COMPRISES PASSING VAPORS OF ACETONE AND AMMONIA IN WEIGHT RATIO BETWEEN 10/1 AND 2/1 OVER A SILICA-ALUMINA CATALYST CONTAINING BETWEEN 5% AND 5/% BY WEIGHT OF ALUMINA AND 95, TO 50% BY WEIGHT OF SILICA AT A TEMPERATURE FROM ABOUT 300*C. TO ABOUT 550*C. 